Handle down payments and overpayments

If a customer sends you more money than he or she owes, there
will be an amount left over after you have applied the payment to
invoices. QuickBooks keeps track of the credit amount so you can
apply it the next time the customer owes you money.

If you're recording a down payment and you are doing more
than one job for the customer, specify both the customer name and
the job name in the Customer:Job field to make sure that QuickBooks
applies the payment to invoices for the correct job.

If the payment is an overpayment, you'll want to apply as
much of the payment as you can to outstanding invoices.